1. Field Of This Invention
This invention relates to a process for the production of 3-picoline.
2. Prior Art
Pyridine bases represent important intermediate products in the chemical industry, as for example in the case of the production of nicotinic acid or nicotinic acid amide. Various processes are known for the production of pyridine bases.
2-Methyl-5-ethylpyridine is currently produced on an industrial scale in the liquid phase process from acetaldehyde or paraldehyde and ammonia in the presence of the most diverse catalysts, such as, ammonium salts. Small quantities of 2- and 4-picoline are obtained as by-products.
2- and 4-picoline are currently produced in gas phase reactions at temperatures of about 400.degree. C. from acetaldehyde and ammonia with the use of solid bed or fluid bed catalysts on the basis of aluminum silicate.
For the production of pyridine as well as of 3-picoline which gains ever greater importance, at the present time gas phase reactions are used--by the addition of formaldehyde to the acetaldehyde, the formation of 2- and 4-picoline is suppressed in favor of 3-picoline. These reactions also take place in the solid bed or fluid bed with aluminum silicate as a catalyst at temperatures of about 400.degree. C. According to these processes, yields of 3-picoline in the order to magnitude of at most 40 to 44 percent are achieved. Beside that, one obtains large quantities of pyridine with such processes.
It is also known that one may start out with unsaturated aldehydes, such as acrolein or crotonaldehyde, instead of saturated aldehydes. These reactions take place at high temperatures in the gaseous phase; the yields are essentially equal in amount as in the case of when saturated aldehydes are used as starting material.